Use a block cursor in overtype mode

LayoutTests/editing/selection/resources/block-cursor-utils.js

+var blockCursorStartPosition;
+var blockCursor;
+var textNode;
+
+function verifyBlockCursorLeftPositionAndWidth(elementId, expected)
+{
+    blockCursorStartPosition = new Array();
+
+    var element = document.getElementById(elementId);
+    textNode = element.firstChild;
+    debug("Verifying block cursor position and width for each position in '" + textNode.nodeValue + "' in a " + element.style.direction + " block");
+
+    for (var i = 0; i < textNode.length; i++) {
+        evalAndLog("getSelection().collapse(textNode, "+i+")");
+
+        blockCursor = internals.selectionBounds();
+        blockCursorStartPosition.push(blockCursor.left);
+
+        if (i > 0 && i < textNode.length) {
+            if (expected[i-1] == ">")
+                shouldBeTrue("blockCursorStartPosition["+(i-1)+"] > blockCursorStartPosition["+i+"]");
+            else
+                shouldBeTrue("blockCursorStartPosition["+(i-1)+"] < blockCursorStartPosition["+i+"]");
+        }
+
+        shouldBeTrue("getSelection().isCollapsed");
+        shouldBeTrue("blockCursor.width > 1");
+        shouldBe("internals.absoluteCaretBounds().width", "1");
+    }
+
+    evalAndLog("getSelection().collapse(textNode, "+i+")");
+    blockCursor = internals.selectionBounds();
+    shouldBeZero("blockCursor.width");
+    shouldBe("internals.absoluteCaretBounds().width", "1");
+    debug("");
+}